The invention proceeds from a surgical instrument for applying implants, in particular bone grafts in the region of the vertebral column, consisting of a shank, a handle and a holder for the implant, which forms the distal instrument part.
With known instruments of this type, for example, the holder for the implant, which is formed as a spike, is rigidly connected to the shank of the instrument, i.e., in an unchangeable alignment to the instrument longitudinal axis. This is also the case with the instrument which is disclosed in FR-A 2 764 795 and described as a key, with which a support body may be implanted between neighboring vertebral bodies and with which the holder is formed as a threaded stem to which the implant is connected by screwing.
With the use of these surgical instruments it is necessary for the location of the defect concerned and the access thereto to lie in the axis direction of the instrument for the purpose of introducing the implant, which makes its application more difficult and demands an exact alignment of the instrument onto the location of operation.
It is the object of the invention to specify a surgical instrument for applying implants, which permits a variably adjustable alignment of the implant in relation to the instrument and operation location, and specifically where required also even during the operation procedure. Furthermore, at the same time the instrument is to permit a simple and secure handling and with regard to the demands on hygiene able to be easily disassembled.
Proceeding from an instrument of the initially mentioned type, this object is achieved according to the invention in that the holder is pivotably mounted relative to the shank and is fixable in its position which is in each case achieved by pivoting.
According to a preferred embodiment of the invention, on the holder there may be provided an essentially spherical bearing body, which is mounted in the shank and which is pivotable about two axes intersecting perpendicularly, and which by way of a rod which runs through the shank and which with its distal end is movable against the periphery of the bearing body, may be fixed by way of clamping.
In order to achieve a rotational fit connection between a handle of the instrument and the bearing body, the bearing body may be provided with a groove running on a circular path of more than 180xc2x0, wherein into the groove engage pins which are fastened to the shank, which lie on the same axis and which form a first pivot axis for the bearing body, and the bearing body with the pins sliding in the groove is pivotable about a second pivot axis which stands perpendicular to the first pivot axis and the plane of the groove.
The fixing of the bearing body by clamping may usefully be made possible in that the distal open end of the shank is drawn inwards and forms a spherically curved annular surface as a shoulder and bearing surface for the bearing body, and that in the distal end region of the rod formed as a tube there is provided an insert whose end projecting out of the rod is formed as a spherically curved annular surface, which by way of distal adjustment of the rod can be brought to bear against the periphery of the bearing body, in order to fix this bearing body and thus also the holder carrying the implant in the respective pivot position by way of a clamping effect.
In the proximal end region of the handle, rigidly connected to the shank, there is provided an inner thread into which a threaded projection of a clamping head is screwed, said head being rigidly connected to the rod. By rotating the clamping head and thus the rod in a first direction, this may be distally adjusted for fixing the bearing body, and reversely by rotating in a second direction may be adjusted proximally, in order thus to lift the clamping effect between the bearing body and the parts engaging it or only to reduce this clamping effect somewhat. The holder thus becomes pivotable and subsequently, after pivoting into a suitable position, may again be fixed by rotating the clamping head in the first direction.
The holder on the proximal side blends into an annular shoulder, forming an abutment for the implant, and via a cylinder projecting through the open end of the shank is rigidly connected to the bearing body. If with the instrument, bone parts or bone grafts are to be applied, it is useful to form the holder as a distally, conically tapering, threaded spike, which may be simply screwed into the implant and which securely holds it.